Live birth in Cretaceous marine lizards (mosasauroids)

  title={Live birth in Cretaceous marine lizards (mosasauroids)},
  author={Michael Wayne Caldwell and M S Lee},
  journal={Proceedings of the Royal Society of London. Series B: Biological Sciences},
  pages={2397 - 2401}
  • M. Caldwell, M. S. Lee
  • Published 7 December 2001
  • Environmental Science, Geography
  • Proceedings of the Royal Society of London. Series B: Biological Sciences
Although live-bearing (viviparity) has evolved around 100 times within reptiles, evidence of it is almost never preserved in the fossil record. Here, we report viviparity in mosasauroids, a group of Cretaceous marine lizards. This is the only known fossil record of live-bearing in squamates (lizards and snakes), and might represent the oldest occurrence of the trait in this diverse group; it is also the only known fossil record of viviparity in reptiles other than ichthyosaurs. An exceptionally… 
A gravid lizard from the Cretaceous of China and the early history of squamate viviparity
This specimen documents the first occurrence of viviparity in a fossil reptile that was largely terrestrial in life, and extends the temporal distribution of the trait in squamates by at least 30 Ma.
Terrestrial Origin of Viviparity in Mesozoic Marine Reptiles Indicated by Early Triassic Embryonic Fossils
The new specimen contains the oldest fossil embryos of Mesozoic marine reptile that are about 10 million years older than previous such records and strongly indicates a terrestrial origin of viviparity, in contrast to the traditional view.
Pelagic neonatal fossils support viviparity and precocial life history of Cretaceous mosasaurs
The recovery of these extremely young specimens from a pelagic setting indicates that even neonatal mosasaurs occupied open oceanic habitats and were likely born in this setting, and shed new light on the ecology of neonatalMosasaurs.
Triassic marine reptiles gave birth to live young
Two gravid specimens of Keichousaurus hui Young from the Middle Triassic of China provide the first unequivocal evidence of reproductive mode and sexual dimorphism in sauropterygians and indicate that viviparity could have been expedited by the evolution of a movable pelvis in pachypleurosaurs.
Evolution of viviparous reproduction in Paleozoic and Mesozoic reptiles.
P paleontological evidence indicates that extinct viviparous reptiles had internal fertilization, amniotic fetal membranes, and placentas that sustained developing embryos via provision of respiratory gases, water, calcium, and possibly organic nutrients.
Viviparity in a Triassic marine archosauromorph reptile
Eggs or embryos have been reported in various groups of fossil reptiles, where viviparity is a common mode of reproduction in aquatic taxa such as the ichthyopterygians, some groups of
Life‐history strategies indicate live‐bearing in Nothosaurus (Sauropterygia)
In Sauropterygia, a diverse group of Mesozoic marine reptiles, fossil evidence of viviparity (live‐bearing) only exists for Pachypleurosauria and Plesiosauria, and was assumed to also be the case for
Live birth in the Devonian period
The oldest record of a live-bearing vertebrate in a new ptyctodontid placoderm, Materpiscis attenboroughi gen. et sp.
Live birth in an archosauromorph reptile
The discovery of a pregnant long-necked marine reptile (Dinocephalosaurus) from the Middle Triassic of southwest China shows live birth in archosauromorphs, and phylogenetic models indicate that Dinocephalosaurus determined the sex of their offspring by sex chromosomes rather than by environmental temperature like crocodilians.
Viviparity and K-Selected Life History in a Mesozoic Marine Plesiosaur (Reptilia, Sauropterygia)
Quantitative analysis indicates that plesiosaurs gave birth to large, probably single progeny, and the combination of viviparity, large offspring size, and small brood number differs markedly from the pattern seen in other marine reptiles but does resemble the K-selected strategy of all extant marine mammals and a few extant lizards.


Evolutionary Origins of Viviparity in the Reptilia. I. Sauria
Reproductive mode data were extracted piecemeal from the literature and superimposed over currently accepted phylogenies to permit estimation of the minimum frequencies with which viviparity (live-bearing) has evolved in lizards, as well as to facilitate analysis of hypotheses that genetic sex-determination of the male-heterogametic type as weil as a tendency towards eggention preadapt a lineage for v Viviparity.
Natural History of Reptilian Development: Constraints on the Evolution of Viviparity
Observed observations are consistent with both a saltation model that posits that the characteristic features of viviparity arise suddenly and simultaneously, and a gradualist model that Posits incremental evolution from one reproductive mode to the other.
Using available data on reproductive modes and phylogenetic relationships within reptiles, the numbers and directions of evolutionary transitions between oviparity and viviparity are measured.
Evolutionary Origins of Viviparity in the Reptilia. II. Serpentes, Amphisbaenia, and Ichthyosauria
The discontinuous distribution of the origins of viviparity among the reptilian families supports the hypothesis that selective pressures, preadaptations, and constraints vary at high taxonomic levels.
The pectoral girdle and forelimb of Carsosaurus marchesetti (Aigialosauridae), with a preliminary phylogenetic analysis of mosasauroids and varanoids
The aigialosaur Carsosaurus marchesetti is represented by a nearly complete skeleton from the Upper Cretaceous (Cenomanian-Turonian) of Slovenia and has proportionally larger propodials than any other aigIALosaur.
II.—On two Specimens of Ichthyosaurus Showing Contained Embryos
The British Museum has not possessed a specimen with contained embryos until now, but this deficiency has now been supplied by the acquisition of two fine skeletons, which are worthy of special notice.
Globaura venusta gen et sp. n and Eoxanta lacertifrons gen. et sp. n. - non-teiid lacertoids from the Late Cretaceous of Mongolia
Two Late Cretaceous Mongolian lizards Eoxanta lacertifrons gen. et sp. n and Globaura venusta gen. n (?middle Campanian) are assigned to Lacertoidea and formation of the anteroventral border of orbit by maxilla is considered synapomorphic for the Scincomorpha.
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  • C. Gans
  • Biology, Environmental Science
  • 1969
Why Study Reptilian Development? The Origin and Development of Oocytes Embryology of Turtles Embryology of Marine Turtles Development of Crocodilians Embryology of the Tuatara Some Developmental
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